At least some wireless electronic systems operate in either an active mode or an idle mode. In active mode, the wireless electronic system transmits and acquires data over a “traffic channel” opened between the wireless electronic system and a “base station.” A traffic channel carries encoded speech or user data, and a base station comprises a radio transceiver in a fixed location. In idle mode, the wireless electronic system acquires data from the base station over a “control channel.” A control channel carries data in the form of broadcast messages sent to each wireless electronic system within a certain distance from a base station. The broadcast messages occur approximately once every 2 seconds, and are not transmitted as a continuous stream of data, but as four “bursts” of data. A burst is a specified time of radio frequency transmission, and represents the physical content of a “timeslot.” A timeslot is a discrete window of time, the duration of which is standardized to provide for regularity in communications. A timeslot has a duration of 3/5200 seconds (577 μs), and is divided into 156.25 symbol periods. One symbol period is enough time to transmit one symbol of information, and for Gaussian minimum shift keying (“GMSK”) modulation, a symbol is equivalent to a bit.
In order to acquire broadcast messages, a wireless electronic system provides power to embedded radio frequency (“RF”) circuitry during the four bursts of each broadcast message. If the broadcast message contains a unique identifier associated with the wireless electronic system, the wireless electronic system will open a traffic channel with the base station to acquire encoded speech or user data. If the broadcast message contains a unique identifier associated with another wireless electronic system, or no unique identifiers at all, the original wireless electronic system need not take any action in response to the broadcast message. Because a small percentage of the total number of broadcast messages transmitted to a particular wireless electronic system daily is actually associated with that particular wireless electronic system, most broadcast messages require no further action from the wireless electronic system. If no further action is required, the RF circuitry is powered down after the four bursts are acquired until the next broadcast message arrives. As such, a significant amount of power is consumed by a wireless electronic system while acquiring messages of no consequence to that wireless electronic system.